It is known to equip machine tools with standby controls which regulate the energy consumption of the machine tool. With the known standby modes, various component parts of a machine tool (drives, control, cooling, hydraulics, etc.) are put together into a sleep mode during nonoperation of the machine tool and often after a certain time, with the aim of saving energy.
Patent specification EP 2 149 828 B1 describes a multistage switch-off mechanism for machines in order to reduce the energy consumption. Accordingly, the machine has the states: “off”, “sleep mode” (only a superordinate control is supplied with electricity), “standby” (a voltage is applied to the control for drives, lamps, etc, for example 24 V), “ready for production” (all production-relevant components, such as drives and auxiliary units, receive power, for example 380 V), “production” (the drives draw the energy necessary for the processing operation, and auxiliary units run continuously). If a machine or system according to patent specification EP 2 149 828 B1 is not being used, it first changes to “ready for production”, then after a determinable period of time to “standby”, and lastly after a further definable period of time automatically to “sleep mode”, and finally it turns itself off fully. According to the aforementioned patent specification, the energy consumption of the machine can be reduced by about 30%. The disclosed device in this case also comprises the possibility of changing the machine from an energy-saving mode back into an operating mode in the case of a corresponding activation event (for example input by a user). In this case, a corresponding activation rule is applied. Whereas the teaching of this specification focuses on automated deactivation of the component parts of the machine in order to achieve a low energy consumption, the reactivation of the machine and the influences thereof on the machine are not considered.
Although previous standby controls function well, they only allow the machine tool to be put into a maximum standby mode. On the one hand, this is very energy-efficient, but on the other hand it increases the warm-up time or impairs the processing accuracy of the machine tool at the beginning of the new start-up. The reason for this is that the heating, or thermal expansion, of the machine components has a great influence on the processing accuracy of the machine tool. Particularly with the current high precision and productivity requirements of modern machine tools (for example milling machines, CNC processing centres), rapid reaching of the optimal operating temperature—at which the required high processing accuracy is achieved—is very important. Current standby controls for machine tools take no account of this fact.